A team led by University of Pennsylvania scientists has discovered three genetic variants that offer the first strong clues as to why glaucoma disproportionately affects Black people.
The variants are common in people with African ancestry and are associated with a significantly higher risk of developing the sight-robbing disease, the researchers found in their study of more than 11,000 volunteers, including 6,300 from the Philadelphia area.
The rest came from elsewhere in the United States, as well as Ghana and Nigeria, recruited by collaborators at other institutions.
More research is needed to determine if these variants — each consisting of just a single “letter” among the 3 billion pairs of letters that spell out the human genome — play a direct role in causing glaucoma.
But if they stand up to scrutiny, the findings someday could be used to develop better treatments and identify people who could benefit from them, said Shefali Setia Verma, one of the lead study authors and an assistant professor at Penn’s Perelman School of Medicine.
“The idea is that this can help identify individuals who are at higher risk before any symptoms occur,” she said.
glaucoma is more common in Black people and, when it occurs, is more likely to lead to blindness
Previous studies have found more than 170 other genetic variants that are involved in glaucoma, a condition in which the optic nerve becomes damaged, often as a result of increased pressure inside the eye.
But most of those studies were conducted among white or Asian populations — despite the fact that glaucoma is more common in Black people and, when it occurs, is more likely to lead to blindness.
And most of the genetic variants discovered in those previous studies turned out to play little or no role in the disease for Black people, illustrating the need for diversity in study populations, said Penn physician-scientist Joan M. O’Brien. “It was a hugely unmet need,” she said.
glaucoma is a condition in which the optic nerve becomes damaged, often as a result of increased pressure inside the eye
The genetic findings also could guide the development of better drugs, O’Brien said.
Currently, physicians treat the disease by trying to lower the pressure inside patients’ eyes, first with medication and later, if needed, surgery.
But those tactics don’t work for everyone in whom the disease is caused by elevated eye pressure, O’Brien said. And in some cases, the disease can occur in people whose eye pressure is normal.
“We know it’s not just the pressure,” she said. “But that’s the only treatment we have to give.”
